1. Technical Field of the Invention
This disclosure relates to a semiconductor memory device and more specifically to a magnetoresistive memory device and method of fabricating the same.
2. Description of the Related Art
A magnetoresistive random access memory (MRAM) includes ferromagnetic layers isolated by a nonmagnetic layer. Data is stored in the MRAM according to a direction of the magnetization vectors. For example, the magnetization vector of one ferromagnetic layer may be fixed or locked by a magnetic field, but the magnetization vector of another ferromagnetic layer may be free to vary depending on the applied magnetic field. Therefore, depending on the relative directions of the magnetization vectors, binary data can be stored. That is, when the magnetization vectors of the ferromagnetic layers are in the same direction (e.g., in a parallel state), the resistance of the MRAM has a minimum value. Conversely, when the magnetization vectors are in opposite direction (e.g., in an anti-parallel state), the resistance of the MRAM has a maximum value. Therefore, the resistance of the ferromagnetic layer is sensed by a sensing current in order to read out data stored in the magnetoresistive memory cell.
Accordingly, to achieve low power dissipation, the magnetic field that changes the direction of the magnetization vector should be efficiently transferred to the magnetoresistive memory cell.
Embodiments of the invention address this and other aspects of the conventional art.